We have recently shown that lipoteichoic acid from Streptococcus pyogenes is biochemically and structurally different from that isolated from an L-form derived from this same coccus. This next year of support will permit the conclusion of a comparative study on the effect of isolated, purified and characterized lipoteichoic acid from this L-form and its parental coccus on various human tissues in tissue culture. If cytotoxic, this study will include structural modifications of these respective lipoteichoic acids to establish what the essential components or features of the molecule are that render it so detrimental. Also, studies will be concluded on the effect changes in the stability of the L-form (from osmotic fragility to osmotic stability) have had on the qualitative and quantitative distribution of its membrane proteins. Finally, this L-form will be investigated for any change in its antibiotic sensitivity pattern before and after being past in immunosuppressed mice. BIBLIOGRAPHIC REFERENCES: Chevion, M., Panos, C., and Paxton, J. "Membrane Studies of Streptococcus pyogenes and Its L-Form Growing in Hypertonic and Physiologically Isotonic Media: An Electron Spin Resonance Spectroscopy Approach" Biochim. Biophys. Acta 426: 288-301 (1976). Fernandes, P.B. and Panos, C. "Wall-less Microbial Isolate from a Human Renal Biopsy" J. Clin. Microbial. 5: 106-107 (1977).